Upgrade from 3.x to 4.x

Important Notes

Before starting the upgrade process, please note:

• Backup everything: Database and files
• Test in staging environment first
• Check extension compatibility with OpenCart 4
• Review theme compatibility

Pre-Upgrade Checklist

1. Backup your store:
   • Database backup
   • File system backup
   • Extension configurations
2. Check compatibility:
   • Verify PHP version compatibility (PHP 8.0+ required)
   • Check if extensions support OpenCart 4
   • Review theme compatibility
3. Prepare for downtime:
   • Schedule upgrade during low-traffic periods
   • Inform customers about maintenance

Upgrade Methods

Method 1: Manual Upgrade

1. Download OpenCart 4
   • Get the latest version from OpenCart website
2. Upload new files
   • Upload all files except:
     • /config.php
     • /admin/config.php
     • /images/ directory
     • /system/storage/ directory
3. Run upgrade script
   • Navigate to yourdomain.com/install
   • Follow the upgrade wizard
4. Update database
   • The upgrade script will automatically update your database schema

Method 2: Extension-Based Upgrade

Some hosting providers offer extension-based upgrades through their control panels.

Post-Upgrade Tasks

1. Clear cache:
   • Delete /system/storage/cache/ contents
   • Clear browser cache
2. Test functionality:
   • Test frontend and backend
   • Verify all extensions work
   • Check payment and shipping methods
3. Update extensions:
   • Install OpenCart 4 compatible versions
   • Configure settings as needed

Common Issues

• Extension compatibility: Some extensions may not work with OpenCart 4
• Theme issues: Custom themes may need updates
• Database errors: Check error logs for any database-related issues

Support

If you encounter issues during upgrade, visit the OpenCart forums for community support.